Flexible container or bladder

ABSTRACT

A self-supporting bladder for use in transporting or storing foods and liquids is manufactured by folding the ends of a cylindrical section and sealing the open portions of the folded cylinder, resulting in a bladder which supports itself when filled.

FIELD OF THE INVENTION

The invention concerns the manufacture and use of self-supportingbladders for use in transporting or storing foods and liquids.

BACKGROUND OF THE INVENTION

It has long been desirable to transport foodstuffs, including grains andother solid foodstuffs and liquids such as cooking oils or potableliquids such as water or wine, in cost efficient, protective containers.It is also understood that these containers should serve to protect thefoodstuffs against both physical damage and contamination. For example,U.S. Pat. No. 4,468,812 to Grosvenor discloses a flexible container witha fabric reinforced rubber body, with an internal lining. The fabricserved to reinforce the rubber against physical damage, and the internallining served to protect the transported product from outsideinfluences, such as contamination by contact and reaction with therubber body, or bacterial infiltration.

The advent of the widespread use of standardized metal containers forshipping goods ultimately led to the use of internal container bags, orbladders, so that liquids could be shipped in such containers, as wellas other foodstuffs needing protection from the environment. However,the use of flexible internal bladders in shipping containers resulted inadditional engineering difficulties. As disclosed in U.S. Pat. No.4,054,226 to Bjelland, et al., use of such flexible internal bladdersresulted in undesirable shifting of cargo during shipping, andundesirable stresses on the internal bladders during loading andunloading of the cargo. Bjelland, et al. discloses one attempt toprovide an internal framework to support such internal bladders, andalso discusses other attempted solutions, such as the bulkheadarrangements disclosed in U.S Pat. Nos. 3,386,605 and 3,696,952.

Although these approaches alleviate some of the concerns involved inusing flexible protective bladders for bulk transportation, each of themrequires additional hardware and space, adding expense and reducing theavailable volume for the shipped goods. Thus, these approaches add costand reduce total shipping capacity.

Further, because the bulkhead and other support methods must be usedwith flexible bladders in shipment, the bladders themselves must befilled or emptied in position. They do not have sufficient structuralintegrity to serve as stand-alone containers, nor do their structurallimitations allow them to be moved in or out of the containers whilefull, or to be left full at a final destination without additionalstructural support.

Accordingly, it is an object of the invention to provide a flexiblebladder for use in containerized shipping which does not requireadditional structural support to maintain the structural integrity ofthe bladder while full.

It is another object of the invention to provide a flexible bladderwhich maximizes the available shipping volume for liquid or solidfoodstuffs carried within containerized volumes.

It is a further object of the invention to allow such flexible bladdersto be deposited while full at a shipping destination without loss ofintegrity and without risk of loss or contamination of the shippedgoods.

SUMMARY OF THE INVENTION

The invention comprises a flexible bladder which is constructed bybeginning with a cylinder of flexible material. The cylinder may beformed by rolling an essentially rectangular section of flexiblematerial into a cylindrical shape, and joining the ends to form acylinder. In the preferred embodiment of the invention, the flexiblematerial used is food grade PVC, such as linear low density polyethylenemade by GSE Lining Technology, Inc., of Houston, Tex., with a coating tomake it acceptable under FDA standards for transporting foodstuffs indirect contact.

Further, if a cylinder is formed by rolling an essentially rectangularpiece of material into a cylinder, it is preferred to join the ends ofthe material together by welding, such as by a wedge-weld. Those ofskill in the art will recognize that other types of welds may be used,or other types of joins could be used, so long as the final join istight, sufficiently strong for the purpose, and does not introduce arisk of contamination to the transported goods.

Formed in this way, the cylinder will have opposing, essentiallycircular openings at a first end and second end. As used herein, thelongitudinal axis of the cylinder is that axis parallel to a line drawnbetween the first open end and the second open end of the cylinder, andthe radial axis is the axis perpendicular to the longitudinal axis.

The invention may be embodied in one of two orientations. In the firstorientation, the radial axis of the cylinder will form the longdimension of the final form, which is preferably an essentiallyrectangular parallelipiped, sized to fit the interior space of acontainer vessel for shipping, or, if to be used solely as a stand-alonecontainer, sized to the desired dimensions. In the second orientation,the longitudinal axis of the cylinder will form the long dimension ofthe final form, which is preferably an essentially rectangularparallelipiped, sized to fit the interior space of a container vesselfor shipping, or, if to be used solely as a stand-alone container, sizedto the desired dimensions. Those of skill in the art will understandthat the radius of the cylinder and its length along its longitudinalaxis will be selected based on the desired orientation and the desireddimensions of the final form of the bladder.

In either orientation, the construction of the bladder requires that thefirst open end and the second open end of the cylinder are folded tocreate a pair of opposed shaped openings, which can be closed with ashaped seal which are shaped to the formed shapes of the opening, andfixed in place by a sealing means, such as a weld. In the preferredembodiment, rod welds are used to seal the shaped seals into the ends ofthe cylinder.

It will be recognized by those of skill in the art that the originalcylinder will be formed by this process into a shape which is notcylindrical, but is preferably a portion of a rectangularparallelipiped. However, throughout this description, the word“cylinder” is used to refer to that portion of the structure whichbegins as a cylinder and is manipulated into other shapes and ultimatelyforms a portion of the body of the flexible bladder. This label is usednot as a limitation to the form of the originally cylindrical body, butrather as a convenient label for a body which is at one point incylindrical form but must be manipulated into other forms for thecreation of the final flexible bladder.

In the first orientation, the cylinder is folded by pressing inward anddown from diametrically opposed points at the first open end of thecylinder, forming an essentially flat body comprised of fourtrapezoidally-shaped segments. The four trapezoidally-shaped segmentscomprise two pairs of segments, with each pair having its major basesessentially parallel and separated by an essentially rectangular gap,and its minor bases forming two of the sides of an irregular octagon.The bases of the first pair of trapezoidally-shaped segments areessentially orthogonal to those of the second pair.

Folded in this way, the first open end of the cylinder is formed into anessentially rectangular open segment, bordered by the first pair oftrapezoidally-shaped segments. It is preferable to trim these twotrapezoidally-shaped segments (the two on the top of the foldedcylinder, if it is laid flat on a surface) to remove triangular segmentsat the four ends of the two major bases of the trapezoidally-shapedsegments. Removing this material makes it easier to fold the outer edgesof the underlying, essentially orthogonal second pair oftrapezoidally-shaped segments upward and inward, and removes excessmaterial which would preclude such a fold from laying flat once made.

A rectangular seal, shaped to match the form of the rectangular opensegment bordered by the first pair of trapezoidally-shaped segments andsized to allow sufficient overlap with those segment to provide asufficient seal against pressure from inside, once the bladder iscompleted. Preferably, the long edges of the rectangular seal are placeunder the long bases of the first pair of trapezoidally-shaped segments,so that the edges of the rectangular seal will be on the “inside” of thebladder. In this way, internal pressures will act to press the seal moretightly against the remainder of the bladder. The rectangular seal ispreferably sized so that the length of its long axis is less than thedistance between the short bases of the second pair of trapezoidallyshaped segments, and preferably shortened from this distance byessentially the total length of the trimmed triangular-shaped segmentspreviously cut from the first pair of trapezoidally-shaped segments. If,as is preferred, these triangular-shaped segments have been trimmed fromthe first pair of trapezoidally-shaped segments, an appropriately sizedrectangular seal can simply be slid into position. Now the outer edgesof the underlying, essentially orthogonal second pair oftrapezoidally-shaped segments are folded upward and inward, covering theends of the rectangular seal. At this juncture the seal can be sealed tothe folded cylinder, preferably by the steps of heat sealing, buffing,and rod welding (or extrusion welding) the edges of the rectangularshaped opening in the folded cylinder to the rectangular seal, similarlysealing the folded-over flaps from the underlying, essentiallyorthogonal second pair of trapezoidally-shaped segments, and sealing theshort diagonal segments between the folded-over flaps and the first pairof trapezoidally shaped segments.

Those of skill in the art will recognize that it is possible to turn thefolded cylinder over, exposing the remaining rectangular shaped opening,and to repeat the trimming and sealing process detailed above to inserta second rectangular seal. However, the two original rectangularopenings were essentially orthogonal to each other, and the resultingshape of the bladder would approximate that of a twisted ball with flatends. While such a shape is possibly useful and not beyond the scope ofthis invention, it is not the preferred result of an essentiallyrectangular parallelipiped.

Accordingly, in the preferred embodiment, the folded cylinder is turnedover and unfolded. Due to the presence of the rectangular seal and theeffects of the prior folds, the unfolded cylinder will have a shapeapproximate to that of an open box. The sides of this structure are nowrefolded, to form the second open end of the cylinder into a shape withan essentially rectangular opening which parallels the shape of thefirst shaped seal. This folding is accomplished by trimming fouressentially triangular-shaped segments from the edge of the second openend of the cylinder at the corners that are formed by pressing the wallof the cylinder into essentially the rectangular shape of the firstshaped seal. The wall of the cylinder is then folded inward atapproximately its midpoint parallel the long axis of the first shapedseal, forming the cylinder into a folded rectangle with essentiallytrapezoidally-shaped ends. This folding creates an essentiallyrectangular shaped opening at the second open end of the cylinder, whichcan be sealed by an appropriately sized, rectangular second shaped sealin effectively the same manner as the first shaped seal.

Those of skill in the art will recognize that the bladder must beequipped with a vent and at least one inlet-outlet valve, to allow thebladder to be used for transporting foodstuffs. Because the first andsecond shaped seals in this first orientation form the intended top andbottom of the bladder, a vent, is preferably centered in the first orsecond shaped seal, which will then become the top of the bladder foroperational purposes. Similarly, a ball valve, such as model numberVSF204FP, manufactured by Banjo Corporation, can be used as aninlet-outlet valve. Those of skill in the art will recognize that aninlet-outlet valve may be positioned on the top of the bladder, or alongthe lower edge of one of the sides. Precise positioning of the vent andthe inlet-outlet valve is a matter of preference and utility, and doesnot affect the scope of this invention. However, the vent andinlet-outlet valve must be appropriately positioned at least before thesecond shaped seal is sealed to the cylinder.

Constructed as detailed above, the bladder thus formed will, when filledthrough the inlet-outlet valve, assume the shape of a rectangularparallelipiped, with sufficient structural integrity that no otherframework is necessary to support it. As those skilled in the art willrecognize, if it is appropriately sized it may be placed inside ashipping container and will thus allow maximum use of the space in sucha container for transporting goods, will simultaneously protecting thegoods from loss or contamination.

In the second orientation, the cylinder is folded by first pressing itflat along its longitudinal axis, then folding a section of cylindernear the first open end to so that the first open end forms anessentially rectangular opening bordered by two essentially equilateraltriangles, oriented so that the bases of the two triangles form thesides of the essentially rectangular opening. Similarly to the proceduredescribed above, it is preferable to trim triangular shaped segmentsfrom the four ends of the bases of the two essentially equilateraltriangles, to create a slot so that the first shaped seal may be moreeasily slid into position, and to facilitate the folding over of theedges at the flat ends of the essentially rectangular opening. A firstshaped seal may then be slid into position. As before, it is preferableto position the first shaped seal so that its edges will be inside thebladder relative to the edges of the first open end of the cylinder, sothat internal pressures will serve to enhance the seal.

Similar to the procedure described above regarding the firstorientation, the flat edges of the first open end of the cylinder arefolded over flat against the first shaped seal, and the first shapedseal is preferably welded in place. Repeating this procedure at thesecond open end of the cylinder with a second shaped seal results in abladder which, when filled, will form a rectangular parallelipiped withthe first and second shaped seals forming the ends, rather than the topand bottom, of the bladder. As discussed above, those of skill in theart will recognize that it is necessary to appropriately position andinstall a vent and an inlet-outlet valve during construction of thebladder.

Those of skill in the art will also recognize that different seal shapesmay be used with modified folding techniques, to form differentvariations on the final shape of the bladder. For example, octagonalseals could be used to create an octagonally-shaped bladder, ortriangular seals could be used to form triangular bladders, or othershapes could be used. These variations can be made without departingfrom the spirit of the invention. However, constraints of conventionalshipping methods and structural integrity do not make such variationspreferable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of the beginning materials of a first embodimentof the invention

Fig. 1B is a oblique view of a cylindrical piece used in constructing afirst embodiments of the invention.

FIG. 1C is an oblique view of the cylindrical piece of Fig. 1B duringthe construction process of a first embodiment of the invention.

FIG. 2A is an oblique view of the cylindrical piece of Fig. 1B duringthe construction process of a first embodiment of the invention.

FIG. 2B is an oblique view of the cylindrical piece of Fig. 1B duringthe construction process of a first embodiment of the invention.

FIG. 2C is an oblique view of the cylindrical piece of Fig. 1B duringthe construction process of a first embodiment of the invention.

FIG. 2D is an oblique view of a first embodiment of the invention in apartially constructed state.

FIG. 3A is an oblique view of a first embodiment during the constructionprocess′ continuation from FIG. 2D.

FIG. 3B is an oblique view of a first embodiment during the constructionprocess′ continuation from FIG. 3A.

FIG. 3C is an oblique view of the final assembly of a first embodiment.

FIG. 4A is a face view of the beginning materials of a second embodimentof the invention.

FIG. 4B is a oblique view of a cylindrical piece used in constructing asecond embodiment of the invention.

FIG. 4C is an oblique view of the cylindrical piece of FIG. 4B duringthe construction process of a second embodiment of the invention..

FIG. 4D is an oblique view of the view of FIG. 4C proceeding further inthe construction process of a second embodiment of the invention.

FIG. 5A is an oblique view of the view of FIG. 4D proceeding further inthe construction process of a second embodiment of the invention.

FIG. 5B is an oblique view of the view of FIG. 5A proceeding further inthe construction process of a second embodiment of the invention.

FIG. 5C is an oblique view of the view of FIG. 5B proceeding further inthe construction process of a second embodiment of the invention.

FIG. 5D is an oblique view of the view of FIG. 5C proceeding further inthe construction process of a second embodiment of the invention.

FIG. 5E is an oblique view of the final assembly of a second embodiment.

DETAILED DESCRIPTION

Referring to FIG. 1, the beginning of construction of a firstorientation of a bladder of the present invention is shown. Anessentially rectangular strip of material 110, such as food-grade PVC,is rolled into a cylindrical shape and formed into a cylinder 114 bywedge-weld 112. Cylinder 114 has a first open end 115 and a second openend 117. Cylinder 114 is then folded at first open end 115 by pressinginward at diametrically opposed positions 116, 118 and folds 120 areformed in the cylinder 114.

Referring to FIG. 2, further steps in the construction of the firstorientation are shown. Folds 220 in cylinder 214 are completed, so thatcylinder 214 lays essentially flat. The folding of cylinder 214 hasformed a first pair of essentially trapezoidally shaped segments 222 anda second pair of essentially trapezoidally shaped segments 224. Eachpair of essentially trapezoidally shaped segments defines an essentiallyrectangular shaped opening; the first pair of essentially trapezoidallyshaped segments 222 defines essentially rectangular shaped opening 226,and the second pair of essentially trapezoidally shaped segments 224defines essentially rectangular shaped opening 228.

It is preferable to trim essentially triangular shaped segments (notshown) from the ends 230, 232 of the first pair of essentiallytrapezoidally shaped segments 222. Such trimming facilitates the foldingof the ends 234, 236 of the second pair of essentially trapezoidallyshaped segments 224, and allows first shaped seal 238 to be easily slidinto position under the edges of the first pair of essentiallytrapezoidally shaped segments 222, as depicted by the directional arrowin FIG. 2B..

With the first shaped seal 238 in position, the ends 234, 236, of thesecond pair of essentially trapezoidally shaped segments 224 are foldedover the first shaped seal 238, as depicted by the directional arrow inFIG. 2C. Rod welds 242 are made to sealably connect first shaped seal238 to the first pair of trapezoidally shaped segments 222, and to sealjoins 240 between the ends 234, 236, of the second pair of essentiallytrapezoidally shaped segments 224 and the first pair of essentiallytrapezoidally shaped segments 222.

Cylinder 214 can then be turned over and unfolded as shown in FIG. 2D.The presence of first shaped seal 238 causes cylinder 214 to form theshape of a rectangular parallelipiped 244, with the open top being thesecond open end 217 of cylinder 214. Triangular segments 248, 250(indicated by dashed lines) are trimmed from the “corners” of cylinder214 to facilitate the folding of second open end 217 of cylinder 214.

Referring now to FIG. 2D and FIG. 3, cylinder 314 (214 of FIG. 2) isfolded again along fold lines 246 of FIG. 2D, allowing cylinder 314 tolay in a folded flat shape and folding second open end 317 of cylinder314 to form an essentially rectangular opening. Second shaped seal 338may then be slid into position, as depicted by the directional arrow ofFIG. 3A. Second shaped seal 338 comprises vent hole 324 for positioningof a vent (not shown) and valve hole 326 for positioning of aninlet-outlet valve (not shown). As discussed previously, the positioningof vents and valves is a matter of engineering preference and needs ofthe particular application, and these hole positions are shown by way ofexample only.

Second shaped seal 338 is positioned so that it lays under essentiallytrapezoidal end segments 316 and 318, and flaps 320 and 322 are foldedover the sides of second shaped seal 338. As with the first shaped seal(238 of FIG. 2), rod welds 328 seal the sides of the second shaped seal338 to the cylinder 314, and also seal joins at the comers.

As shown in FIG. 3C, when the bladder 330 is filled, it now forms anessentially rectangular parallelipiped.

Referring to FIG. 4, the beginning steps to manufacture a secondorientation of the invention are shown. A sheet 410 of material such asfood-grade PVC is rolled into a cylinder 414 with a first open end 416and a second open end 418, and fixed in that shape with wedge welds 412.Those skilled in the art will recognize that the circumference ofcylinder 414 is limited by the size of sheet 410, and that, if necessaryto achieve the desired size for the final bladder, multiple sheets ofmaterial can be joined together, as by wedge-welding, to form asufficiently large sheet. Cylinder 414 is then flattened along itslongitudinal axis, as depicted by the directional arrows in FIG. 4C. Asection 420 of cylinder 414 is folded near first open end 416, asdepicted by the directional arrow of FIG. 4D.

Referring to FIG. 5, the first open end 516 of cylinder 514 is openedand one-half of the material 524 is folded back (as shown by thedirectional arrow of Fig. SA) along fold line A-A′, while the sides arefolded inward to form essentially triangular segments 526, which definea rectangular slot 528.

Triangular sections (not shown) are preferably trimmed off of thecorners 530, 532 of the essentially triangular sections 526, allowingroom to easily slide first shaped seal 534 into position as depicted bythe directional arrow of FIG. 5B. With first shaped seal 534 in positionin the first open end 516 of cylinder 514, edges 536 and 536 are foldedover first shaped seal 534 as depicted by the directional arrows of Fig.5C. Rod welds 540 are preferably used to seal the first shaped seal 534into the first open end 516 of cylinder 514, and to seal the joinsbetween the essentially triangular sections 526 and edges 536 and 538.

Installation of the second shaped seal (not shown) involves repeatingthe steps depicted in FIGS. 4D, 5A, 5B, 5C, and 5D and described aboveat the second open end (418 of FIG. 4B) of the cylinder 514. As shown inFIG. 5E, when filled the cylinder 514 will be formed into an essentiallyrectangular parallelipiped.

As with the first orientation, a vent hole 542 and inlet-outlet valvehole 544 (or 546 if a lower-end position is used for the inlet-outletvalve) should be provided, and the appropriate internal hardwareinstalled before the cylinder 514 is completely sealed.

The above examples are included for demonstration purposes only and notas limitations on the scope of the invention. Other variations in theconstruction of the invention may be made without departing from thespirit of the invention, and those of skill in the art will recognizethat these descriptions are provide by way of example only.

1. A method of forming a container from a flexible material, comprisingforming a cylinder from a flexible material so that said cylinder has afirst open end and a second open end, folding said first open end ofsaid cylinder to create a first shaped opening, sealing said firstshaped opening with a first shaped seal, folding said second open end ofsaid cylinder to create a second shaped opening, and sealing said secondshaped opening with a second shaped seal.
 2. The method of claim 1,wherein the step of folding said first open end of said cylinder tocreate a first shaped opening includes the step of forming said firstshaped opening to a rectangular shape.
 3. The method of claim 1, whereinthe step of folding said second open end of said cylinder to create asecond shaped opening includes the step of forming said second shapedopening to a rectangular shape.
 4. The method of claim 1, wherein thestep of folding the first open end of said cylinder to create a firstshaped opening includes the step of forming said first shaped opening toa first rectangular shape and the step of folding said second open endof said cylinder to create a second shaped opening includes the step offorming said second shaped opening to a second rectangular shape.
 5. Themethod of claim 4, additionally comprising the step of forming saidfirst rectangular shape and said second rectangular shape so that onedimension of each of said rectangular shapes is longer than theperpendicular dimension of that shape.
 6. The method of claim 4,additionally comprising the step of orienting said first rectangularshape and said second rectangular shape to be substantially parallel. 7.The method of claim 5, additionally comprising the step of orientingsaid first rectangular shape and said second rectangular shape so thatthe longer dimension of said first rectangular shape is substantiallyparallel to the longer dimension of said second rectangular shape. 8.The method of claim 1, wherein said step of sealing said first shapedopening with a first shaped seal additionally comprises the step ofwelding said first shaped seal to said cylinder.
 9. The method of claim1, wherein said step of sealing said second shaped opening with a secondshaped seal additionally comprises the step of welding said secondshaped seal to said cylinder.
 10. A container formed of flexiblematerial comprising a cylindrical body, a first shaped seal, whereinsaid first shaped seal is sealably joined to a first folded end of saidcylindrical body, and a second shaped seal, wherein said first shapedseal is sealably joined to a second folded end of said cylindrical body.11. The container of claim 10, wherein said first shaped seal isrectangular.
 12. The container of claim 10, wherein said second shapedseal is rectangular.
 13. The container of claim 10, wherein said firstshaped seal is square.
 14. The container of claim 10, wherein saidsecond shaped seal is square.
 15. The container of claim 10, whereinsaid first shaped seal is welded to said first folded end of saidcylindrical body.
 16. The container of claim 10, wherein said secondshaped seal is welded to said first folded end of said cylindrical body.